1. Field of the Invention
The present invention relates to a brake system for slowing or stopping a rotational driving shaft of a power system, and more particularly to a hydraulic brake system for accurately slowing or stopping a rotational driving shaft of a power system with a physical force which is produced due to an incompressible fluid characteristic.
2. Description of the Prior Art
The patent application for a hydraulic brake system which is capable of solving general problems of a conventional friction brake device has been filed by the same applicant with the Korean Industrial Property Office on Oct. 7, 1996 (Application No. 96-0444192), and granted a patent on Nov. 25, 1998 (Patent No.: 178774) which will be described briefly below.
According to the Korean Patent No. 178774, the hydraulic brake system includes a casing having a hydraulic oil inlet which is opened/closed by a bolt type cover, a piston section which is a sliding member disposed in the casing and has a piston shaft whose both ends protrude outward, a hydraulic pressure controlling ball valve disposed in a hydraulic oil passage in the casing for controlling the flow rate of hydraulic oil, a controlling lever which is a pivot member mounted on the outer surface of the casing for controlling the hydraulic pressure controlling ball valve, a movement section for driving the controlling lever, a brake section connected to the rear end of the piston shaft of the piston device for stopping the rotational driving shaft, and a protective box for surrounding the casing and brake device.
The hydraulic brake system constructed as above normally permits the hydraulic oil reserved in the hydraulic oil chamber to flow without any disturbance. Then when the brake is operated, by disturbing or stopping the hydraulic oil flow by operating the hydraulic pressure controlling ball valve, the hydraulic brake system slows or stops the rotational driving shaft of the power system through the brake section with a physical force which is produced due to the resistance or stoppage of the hydraulic oil flow, and thereby performs an efficient brake operation. Accordingly, even after a long period of continuous using time, the brake system has no problems such as breakage or non-operation. Further, in this brake system which is constructed by a new concept quite different from the conventional friction brake system, since there is no need to employ brake pads, there is no inconvenience of replacing the brake pads. Also, without having to employ a servo assisted brake, the hydraulic brake system can precisely perform the brake operation by only one process.
The above hydraulic brake system, however, has a shortcoming of having abrasions between friction sliding sections and accordingly a low persistence, since it has no lubricating structure for the friction sliding sections of the piston and brake sections.
Further, since the above hydraulic brake system has no safety device employed for any abnormal events such as hydraulic oil leakage, etc., the brake operation can not be performed when an abnormality occurs, accordingly having the high possibility of allowing an accident.
Further, since a link of the brake section and the piston shaft of the piston section are connected with each other by a guiding member which is generally in the shape of a shaft, unnecessary rolling occurs in addition to the reciprocal linear movement of the piston shaft. Accordingly, the piston shaft is curved by excessive force exerted thereto, and brake force is inaccurately controlled.
The present invention has been developed to overcome the above-mentioned problems of the prior art, and accordingly it is an object of the present invention to provide a hydraulic brake system capable of controlling abrasions between friction sliding sections by lubricating means for supplying oil for lubrication to the respective friction sliding members.
Another object of the present invention is to provide a hydraulic brake system capable of not only controlling the flow rate of hydraulic oil in the reservoir, but also supplementing hydraulic oil for an emergency brake operation in the event of a hydraulic oil leakage.
Still another object of the present invention is to provide a hydraulic brake system capable of controlling the brake force more accurately by transmitting link movement into the accurate reciprocal linear movement of the piston section.
The above object is accomplished by a hydraulic brake system according to the present invention, including: a hydraulic oil reservoir having a hydraulic oil chamber filled with hydraulic oil; a piston device disposed in the hydraulic oil reservoir for being reciprocally and linearly moved; a link device disposed between the piston device and an eccentric cam formed on the rotational driving shaft of the power system, the link device moving in accordance with the rotation of the rotational driving shaft in a manner of tracing a circular arc path upward and downward and forward and backward; a connecting device for connecting the link device and the piston device in a manner that link device and the piston device are moved in relation to each other; a flow rate controlling section disposed in the hydraulic oil passage of the hydraulic oil reservoir for selectively stopping the piston device by controlling the flow rate of hydraulic oil; a protective casing for holding , thus supporting the above-mentioned respective components, the protective casing filled with hydraulic oil; and a lubricating section for pumping hydraulic oil of the protective casing to the friction sliding sections of the rotational driving shaft, the link device, and the connecting device, respectively.
Such a hydraulic brake system according to the present invention slows or stops the rotational driving shaft by disturbing or stopping the flow of the hydraulic oil of the hydraulic chamber by using a flow rate controlling section, and accordingly stopping the piston device and thus restricting the link device which is moved in relation to the piston device.
According to a preferred embodiment of the present invention, the link device includes a large-diameter section connected with the eccentric cam of the rotational driving shaft and a small-diameter section which is tapered. Further, the link device is bisected by the centerline of the eccentric cam of the rotational driving shaft into first and second link members, which are fastened by a pair of screws. Accordingly, the link device can be assembled more easily.
The connecting device includes a connecting member having a connecting hole though which the piston rod is connected, and a tapered connecting section connected with the small-diameter section of the link device for transmitting the movement of the link device into the reciprocal linear movement of the piston rod; a first guiding member fastened to the inner wall of the protective casing, having a guiding section accommodated in a sliding hole formed on the upper portion of the connecting member, the first guiding member for guiding the sliding movement of the connecting member from both sides of the connecting member; and a second guiding member having first and second guiding holes to which first and second guiding protrusions, respectively, protruding from the lower side of the connecting hole of the connecting member and form the middle portion of the connecting portion are accommodated, the second guiding member being fastened to the first guiding member by a plurality of screws. Accordingly, undesired force to other directions different from the linear direction of the piston rod is not applied, and bending of the piston rod is prevented, and the brake force is controlled more accurately.
The lubricating section includes: a second cylinder having a hydraulic oil suction hole and a discharge hole formed thereon vertically opposite to each other, the second cylinder extending from a side of the cylinder; a second piston extending from the piston to be inserted into and withdrawn out of the second cylinder according to the reciprocal linear movement of the piston for forming suction and discharging pressure in the second cylinder; a hydraulic oil suction pipe connected to the hydraulic oil suction hole of the second cylinder for conveying hydraulic oil of the protective casing to the interior of the second cylinder by the suctioning pressure of the second cylinder; a hydraulic oil feeding pipe disposed between the hydraulic oil discharge hole of the second cylinder and friction sliding sections of the above-mentioned respective components; and back flow preventing check valves respectively disposed in the hydraulic oil suction hole and the discharge hole of the second cylinder. Since hydraulic oil is supplied to the respective friction sliding sections for lubrication, possible abrasions of the friction sliding sections are prevented, and inner persistence of the system is improved.
According to another preferred embodiment of the present invention, the hydraulic brake system further includes a hydraulic oil supplementing section for supplementing hydraulic oil of the hydraulic oil reservoir in the event of a hydraulic oil leakage.
The hydraulic oil supplementing section includes: a secondary hydraulic oil reservoir disposed on the inner upper side of the protective casing for sucking in the hydraulic oil of the protective casing, and for reserving the sucked hydraulic oil therein; a hydraulic oil feeding pipe for connecting the secondary hydraulic oil reservoir and the hydraulic oil chamber of the hydraulic oil reservoir; and a valve disposed around the hydraulic oil feeding pipe for selectively blocking the hydraulic oil supply.
The valve includes: a valve body having upper and lower valve holes which have a plurality of slits radially formed thereon; and a ball positioned in the lower valve hole of the valve body at a predetermined distance from the upper valve hole for closing the valve hole by being elevated when the pressure of the hydraulic oil reservoir increases. Accordingly, consistent amount of hydraulic oil is maintained in the hydraulic oil reservoir, and hydraulic oil is automatically supplemented in the event of a hydraulic oil leakage for an emergency brake operation.
According to another preferred embodiment, brake forces are exerted to two portions of the rotational driving shaft of the power system. Accordingly, greater brake force is obtained, and more accurate and balanced brake operation is guaranteed.